Sedentary behaviors and light-intensity activities in relation to colorectal cancer risk

Different operationalizations of the 2018 WCRF/AICR cancer prevention recommendations and risk of cancer

BACKGROUND

The standardized scoring system assessing adherence to the 2018 World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) cancer prevention recommendations assigns equal weight for each recommendation, thereby giving higher weight to dietary factors collectively (5 points) than adiposity (1 point) and physical activity (1 point). An alternative score assigning equal weights to the adiposity, physical activity, alcohol, and other dietary (composite) recommendations may better predict cancer associations.

METHODS

We examined associations between standardized and alternative scores with cancer risk in two US prospective cohorts. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox regression.

RESULTS

During 28 years of follow-up, 16,342 incident cancer cases in women and 8729 cases in men occurred. Individuals in the highest versus lowest quintile of the standardized score had a reduced overall cancer risk (women: HR = 0.89, 95% CI: 0.85, 0.94; men: HR = 0.87, 95% CI: 0.81, 0.94). Results were slightly stronger for the alternative score (women: HR = 0.83, 95% CI: 0.79, 0.87; men: HR = 0.81, 95% CI: 0.75, 0.86). Similar patterns were observed for obesity-related, alcohol-related, smoking-related, and digestive system cancers.

CONCLUSIONS

Greater adherence to the WCRF/AICR cancer prevention recommendations was associated with lower cancer risk. A score assigning equal weights to the adiposity, physical activity, alcohol, and all remaining diet components yielded stronger associations than the standardized score.

Early-Onset Colorectal Cancer: Current Insights

Over the past decade, the incidence of colorectal cancer has increased in individuals under the age of 50 years. Meanwhile, the incidence has gradually decreased in the older population. As described herein, we reviewed the available literature to summarize the current landscape of early-onset colorectal cancer, including risk factors, clinicopathological presentation, genetic makeup of patients, and management. Currently, early-onset colorectal cancer is treated similarly as late-onset colorectal cancer, yet the available literature shows that early-onset colorectal cancer is more aggressive and different, and this remains a significant unmet need. A detailed understanding of early-onset colorectal cancer is needed to identify risk factors for the increased incidence and tailor treatments accordingly.

Genetic associations of leisure sedentary behaviors and the risk of 15 site-specific cancers: A Mendelian randomization study

BACKGROUND AND AIMS

Leisure sedentary behavior (LSB) is associated with the risk of cancer, but the causal relationship between them has not been clarified. The aim of this study was to assess the potential causal association between LSB and risk of 15 site-specific cancers.

METHODS

The causal association between LSB and cancer were assessed with univariate Mendelian randomization (UVMR) and multivariate Mendelian randomization (MVMR). 194 SNPs associated with LSB (from the UK Biobank 408,815 individuals) were adopted as the instrument variables. Sensitivity analyses were performed to ensure the robustness of the results.

RESULTS

UVMR analysis revealed that television watching significantly increased the risk of endometrial cancer (OR = 1.29, 95% CI = 1.02-1.64, p = 0.04) (mainly the endometrioid histology [OR = 1.28, 95% CI = 1.02-1.60, p = 0.031])，breast cancer (OR = 1.16, 95% CI = 1.04-1.30, p = 0.007) (both ER+ breast cancer [OR = 1.17, 95% CI = 1.03-1.33, p = 0.015], and ER- breast cancer [OR = 1.55, 95% CI = 1.26-1.89, p = 2.23 × 10^-5 ]). Although causal association was not found between television watching and ovarian cancer, it was seen in low grade and low malignant potential serous ovarian cancer (OR = 1.49, 95% CI = 1.07-2.08, p = 0.018). However, significant results were not obtained in the UVMR analysis between driving, computer use and the 15 types of cancer. Further MVMR analysis indicated that the above results are independent from most metabolic factors and dietary habits, but mediated by educational attainment.

CONCLUSION

LSB in form of television watching has independent causal association with the risk of endometrial cancer, breast cancer, and ovarian cancer.

Association Between Family/Neighborhood Cancer Risk Factors and Adolescent Dietary Behaviors: A Parent-Adolescent Dyadic Analysis

Objective. This cross-sectional study examined associations between adolescent dietary behaviors and family/home environments with parent-adolescent dyadic analysis. Methods. Secondary data were analyzed for adolescents and their parents who participated in the 2014 Family Life, Activity, Sun, Health, and Eating (FLASHE) study. Relationships between adolescent and parent intake of convenience/fast-food, fruits/vegetables, and sugar, as well as family/community and mealtime environments, were examined using Pearson's correlations, 2-sample t tests, analysis of variance, and general linear model analyses. Results. Among this nationwide parent-adolescent dyad sample (N = 1890), a moderate relationship between parent and adolescent consumption of convenience/fast-foods (r = 0.426) and fruits/vegetables (r = 0.416) was found. Adolescent convenience/fast-foods intake differed by sex, neighborhood socioeconomic status, meals eaten with family, and meals eaten in front of the TV (P < .001 for all) as well as race/ethnicity (P = .004). Adolescent fruit/vegetable intake differed by home location (P = .029), school location (P = .032), meals eaten together with family, meals eaten in front of the TV, and body mass index category (P < .001 for all). Generalized linear models revealed multiple predictors of adolescent dietary behaviors. Conclusion. Findings suggest dynamic relationships between adolescent and parent dietary cancer risk factors and adolescent fruit/vegetable consumption disparities by multiple environmental factors. Interventions targeting adolescent-parent dyads may help reduce cancer risk associated with diet.

Modelling the potential health and economic benefits of reducing population sitting time in Australia

BACKGROUND

Strong evidence indicates that excessive time spent sitting (sedentary behaviour) is detrimentally associated with multiple chronic diseases. Sedentary behaviour is prevalent among adults in Australia and has increased during the COVID-19 pandemic. Estimating the potential health benefits and healthcare cost saving associated with reductions in population sitting time could be useful for the development of public health initiatives.

METHODS

A sedentary behaviour model was developed and incorporated into an existing proportional, multi-state, life table Markov model (ACE-Obesity Policy model). This model simulates the 2019 Australian population (age 18 years and above) and estimates the incidence, prevalence and mortality of five diseases associated with sedentary behaviour (type 2 diabetes, stroke, endometrial, breast and colorectal cancer). Key model inputs included population sitting time estimates from the Australian National Health Survey 2014-2015, healthcare cost data from the Australian Institute of Health and Welfare (2015) and relative risk estimates assessed by conducting literature reviews and meta-analyses. Scenario analyses estimated the potential change in disease incidence as a result of changes in population sitting time. This, in turn, resulted in estimated improvements in long term health outcomes (Health-adjusted life years (HALYs)) and healthcare cost-savings.

RESULTS

According to the model, if all Australian adults sat no more than 4 h per day, the total HALYs gained would be approximately 17,211 with health care cost savings of approximately A$185 million over one year. Under a more feasible scenario, where sitting time was reduced in adults who sit 4 or more hours per day by approximately 36 min per person per day (based on the results of the Stand Up Victoria randomised controlled trial), potential HALYs gained were estimated to be 3,670 and healthcare cost saving could reach A$39 million over one year.

CONCLUSIONS

Excessive sedentary time results in considerable population health burden in Australia. This paper describes the development of the first Australian sedentary behaviour model that can be used to predict the long term consequences of interventions targeted at reducing sedentary behaviour through reductions in sitting time. These estimates may be used by decision makers when prioritising healthcare resources and investing in preventative public health initiatives.

Association of sedentary work with colon and rectal cancer: systematic review and meta-analysis

OBJECTIVES

There has been no research on sedentary behaviour in the occupational domain that occupies a large portion of the daily life.

METHODS

We conducted a meta-analysis to investigate the association between sedentary work and colorectal cancer. We searched PubMed, Embase and Cochrane databases up to 12 August 2020 for peer-reviewed journal articles that assessed the association between sedentary work and colon or rectal cancer. Pooled estimates of ORs were obtained using random effects models. Statistical tests for publication bias, heterogeneity and sensitivity analysis were applied.

RESULTS

Of the 5 381 studies initially identified, 23 studies with 64 reports were eligible for inclusion. Sedentary work significantly increased the risk of colon cancer (pooled OR=1.21, 95% CI 1.11 to 1.31, p value ≤0.0001) and rectal cancer (pooled OR=1.08, 95% CI 1.00 to 1.16, p value=0.0395). The adjustment for leisure time physical activity attenuated the association and made the risk estimates non-significant for sedentary behaviour, but the association was independent of sex, control of body mass index and assessment of sedentary behaviour.

CONCLUSIONS

We found evidence of association between sedentary work and the risk of colon or rectal cancer. Limiting excessive sedentary work could be an important means of preventing colon and rectal cancer.

Television Viewing Time and the Risk of Colorectal Cancer Mortality among Japanese Population: The JACC Study

PURPOSE

Sedentary behavior attributes to the increased risk of some cancers and all-cause mortality. The evidence is limited for the association between television (TV) viewing time, a major sedentary behavior, and risk of colorectal cancer death. We aimed to examine this association in Japanese population.

Materials and Methods

A prospective cohort study encompassed of 90,834 men and women aged 40-79 years with no prior history of colorectal cancer who completed a self-administered food frequency questionnaire, and provided their TV viewing information. The participants were followed-up from 1988-1990 to the end of 2009. The hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated by the Cox proportional hazard regression for risk of colorectal cancer mortality according to TV viewing time.

RESULTS

During the median 19.1-year follow-up period, we documented 749 (385 men and 364 women) colorectal cancer deaths. The multivariable-adjusted HRs for mortality from colorectal cancer were 1.11 (0.88-1.41) for 1.5 to < 3 hr/day, 1.14 (0.91-1.42) for 3 to < 4.5 hr/day and 1.33 (1.02-1.73) for ≥ 4.5 hr/day in comparison to < 1.5 hr/day TV watching; p-trend=0.038, and that for 1-hour increment in TV viewing time was 1.06 (1.01-1.11). Moreover, the multivariable-adjusted HR (95%CI) of colon cancer for 1-hour increment in TV viewing time was 1.07 (1.02-1.13). Age, body mass index, and level of leisure-physical activity did not show significant effect modifications on the observed associations.

CONCLUSION

TV viewing time is associated with the increased risk of colorectal cancer mortality among Japanese population, more specifically colon rather than rectal cancer.

de Pancorbo M, Palencia-Madrid L, Garcia-Etxebarria K, Rocandio AM, Arroyo-Izaga M. Gene-Diet Interactions in Colorectal Cancer: Survey Design, Instruments, Participants and Descriptive Data of a Case-Control Study in the Basque Country

Epidemiologic studies have revealed inconsistent evidence of gene-diet interaction in relation to colorectal cancer (CRC). The aim of this study was to analyze them in a sample of cases and controls from the population-based bowel cancer screening program of the Osakidetza/Basque Health Service. This study analyzed dietetic, genetic, demographic, socioeconomic factors and lifestyles. In the present manuscript, the survey design, sampling, instruments, measurements and related quality management were presented. Moreover, we analyze differences between cases and controls in some data, especially those related to diet. The participants were 308 cases and 308 age- and sex-matched subjects as controls. Cases were more likely than controls to have overweight/obesity (67.5% vs. 58.1%, p < 0.05), a lower intake of vitamin B2 (0.86 ± 0.23 vs. 0.92 ± 0.23 mg/1000 kcal, p < 0.01) and calcium:phosphorus ratio (0.62 ± 0.12 vs. 0.65 ± 0.13, p < 0.01). A higher proportion of cases than controls did not meet the Nutritional Objectives for saturated fatty acids (85.7% vs. 67.5%, p < 0.001) or cholesterol (35.4% vs. 25.0%, p < 0.01). In conclusion, the present study provides valuable data for analyzing the complexity of gene-diet interaction in relation to CRC. The results presented here suggest that overweight/obesity and a high intake of certain dietary components, especially saturated fatty acids and cholesterol, are more frequent in cases than in controls.

Occupational sitting time and subsequent risk of cancer: The Japan Public Health Center-based Prospective Study

Although occupational sitting time has been associated with adverse health outcomes and mortality, the association with cancer incidence remains unknown. This study investigated the association between occupational sitting time and risk of total and site‐specific cancer in a Japanese population. We evaluated 33 307 participants aged 50‐79 years who responded to a questionnaire in 2000‐2003 in the Japan Public Health Center‐based Prospective Study and were followed until 2013. Participants were grouped by sitting time at work. Hazard ratio (HR) and 95% confidence interval (CI) of cancer incidence were calculated with adjustment for potential confounders including moderate‐to‐vigorous physical activity. During 10.2 years of follow‐up, 3807 newly diagnosed cases of cancer were identified. Occupational sitting time was marginally associated with total cancer, with multivariable HRs for the ≥7 h/d vs 1 to <3 h/d category of 1.12 (95% CI, 0.99‐1.26; P for trend = .071) in men, but not women. Among findings for cancers at specific sites, long occupational sitting time was associated with increased risk of pancreas cancer, with multivariable HRs for the ≥7 h/d vs 1 to <3 h/d category of 2.25 (95% CI, 1.17‐4.34; P for trend = .021) in men, and lung cancer, with multivariable HRs for the ≥7 h/d vs 1 to <3 h/d category of 2.80 (95% CI, 1.33‐5.90; P for trend = .013) in women. Extended sitting time at work was associated with an increased risk of pancreas cancer in men and lung cancer in women.

Association of Obesity With Risk of Early-Onset Colorectal Cancer Among Women

Importance

Colorectal cancer (CRC) incidence and mortality among individuals younger than 50 years (early-onset CRC) are increasing. The reasons for such increases are largely unknown, although the increasing prevalence of obesity may be partially responsible.

Objective

To investigate prospectively the association between obesity and weight gain since early adulthood with the risk of early-onset CRC.

Design, Setting, and Participants

The Nurses' Health Study II is a prospective, ongoing cohort study of US female nurses aged 25 to 42 years at study enrollment (1989). A total of 85 256 women free of cancer and inflammatory bowel disease at enrollment were included in this analysis, with follow-up through December 31, 2011. Validated anthropomorphic measures and lifestyle information were self-reported biennially. Statistical analysis was performed from June 12, 2017, to June 28, 2018.

Exposures

Current body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared), BMI at 18 years of age, and weight gain since 18 years of age.

Main Outcomes and Measures

Relative risk (RR) for incident early-onset CRC.

Results

Among the 85 256 women studied, 114 cases of early-onset CRC were documented (median age at diagnosis, 45 years; interquartile range, 41-47 years) during 1 196 452 person-years of follow-up. Compared with women with a BMI of 18.5 to 22.9, the multivariable RR was 1.37 (95% CI, 0.81-2.30) for overweight women (BMI, 25.0-29.9) and 1.93 (95% CI, 1.15-3.25) for obese women (BMI, ≥30.0). The RR for each 5-unit increment in BMI was 1.20 (95% CI, 1.05-1.38; P = .01 for trend). Similar associations were observed among women without a family history of CRC and without lower endoscopy within the past 10 years. Both BMI at 18 years of age and weight gain since 18 years of age contributed to this observation. Compared with women with a BMI of 18.5 to 20.9 at 18 years of age, the RR of early-onset CRC was 1.32 (95% CI, 0.80-2.16) for women with a BMI of 21.0 to 22.9 and 1.63 (95% CI, 1.01-2.61) for women with a BMI of 23.0 or greater at 18 years of age (P = .66 for trend). Compared with women who had gained less than 5.0 kg or had lost weight, the RR of early-onset CRC was 1.65 (95% CI, 0.96-2.81) for women gaining 20.0 to 39.9 kg and 2.15 (95% CI, 1.01-4.55) for women gaining 40.0 kg or more (P = .007 for trend).

Conclusions and Relevance

Obesity was associated with an increased risk of early-onset CRC among women. Further investigations among men and to elucidate the underlying biological mechanisms are warranted.

Calcium intake and colon cancer risk subtypes by tumor molecular characteristics

BACKGROUND

A preventive potential of high calcium intake against colorectal cancer has been indicated for distal colon cancer, which is inversely associated with high-level CpG island methylator phenotype (CIMP), high-level microsatellite instability (MSI), and BRAF and PIK3CA mutations. In addition, BRAF mutation is strongly inversely correlated with KRAS mutation. We hypothesized that the association between calcium intake and colon cancer risk might vary by these molecular features.

METHODS

We prospectively followed 88,506 women from the Nurses' Health Study and 47,733 men from the Health Professionals Follow-up Study for up to 30 years. Duplication-method Cox proportional cause-specific hazards regression was used to estimate multivariable hazard ratios (HRs), and 95% confidence intervals (95% CIs) for the associations between calcium intake and the risk of colon cancer subtypes. By Bonferroni correction, the α-level was adjusted to 0.01.

RESULTS

Based on 853 colon cancer cases, the inverse association between dietary calcium intake and colon cancer risk differed by CIMP status (p_{heterogeneity} = 0.01). Per each 300 mg/day increase in intake, multivariable HRs were 0.84 (95% CI 0.76-0.94) for CIMP-negative/low and 1.12 (95% CI 0.93-1.34) for CIMP-high. Similar differential associations were suggested for MSI subtypes (p_{heterogeneity} = 0.02), with the corresponding HR being 0.86 (95% CI 0.77-0.95) for non-MSI-high and 1.10 (95% CI 0.92-1.32) for MSI-high. No differential associations were observed by BRAF, KRAS, or PIK3CA mutations.

CONCLUSION

The inverse association between dietary calcium intake and colon cancer risk may be specific to CIMP-negative/low and possibly non-MSI-high subtypes.

Sedentary Behaviors, TV Viewing Time, and Risk of Young-Onset Colorectal Cancer

Background

Colorectal cancer (CRC) diagnosed before age 50 years, or young-onset CRC, is increasing globally with undefined etiology. A sedentary lifestyle is an emerging risk factor for CRC after age 50 years, but its role in young-onset CRC is unknown.

Methods

We prospectively evaluated sedentary behaviors, primarily time watching television (TV), and risk of young-onset CRC among 89 278 women in the Nurses' Health Study II ages 25-42 years at recruitment (1991-2011). We used Cox proportional hazards modelling to estimate relative risks (RR) and 95% confidence intervals (CIs). Statistical tests were two-sided.

Results

We documented 118 young-onset CRCs over 1 262 540 person-years. Sedentary TV viewing time was statistically significantly associated with increased risk of young-onset CRC, after adjusting for putative risk factors, including obesity and physical activity. Compared 7 hours, women with 7.1-14 hours per week of TV time had a multivariable relative risk (RR) of 1.12 (95% confidence interval [CI] = 0.72 to 1.75), further increased for greater than14 hours per week (RR = 1.69, 95% CI = 1.07 to 2.67, P _trend = .03). This association was observed among participants without a CRC family history and was more pronounced for rectal cancer (RR for >14 vs <7 hours per week 2.44, 95% CI = 1.03 to 5.78, P _trend = .04). Overweight or obese participants may be more susceptible.

Conclusion

Independent of exercise and obesity, prolonged sedentary TV viewing time, a surrogate for a more inactive lifestyle, was associated with increased risk of young-onset CRC, particularly of the rectum. These findings provide further evidence on the importance of maintaining an active lifestyle.

Association of physical activity and sitting time with incident colorectal cancer in postmenopausal women

Findings from epidemiological studies have found that physical activity (PA) is associated with a lower risk of colorectal cancer (CRC). Recent studies have found an increased CRC risk with higher sitting time (ST); however, many studies did not include PA as a potential confounder. The objective of this project was to investigate the independent and combined associations of ST and PA with the risk of incident CRC, specifically colon and rectal cancer. Participants in the Women's Health Initiative Observational Study (n=74 870), 50-79 years of age self-reported ST and PA at baseline, years 3 and 6. Incident CRC was the primary outcome; colon and rectal cancers were the secondary outcomes, which were centrally adjudicated. Over a 13-year follow-up period, 1145 incident cases of CRC were documented. A positive age-adjusted association was found between higher ST (≥10 vs. <5 h/day) and CRC (P for trend=0.04) and colon cancer (P for trend=0.05); however, these associations were attenuated and no longer significant in multivariable-adjusted models. Compared with inactive women (≤1.7 MET-h/week), the multivariable risk of CRC in the high PA (>20 MET-h/week) group was 0.81 (95% confidence interval: 0.66-1.00; P for trend 0.04). Compared with inactive women with high ST (≥10 h/day), there was a trend toward reduced multivariable CRC risks with higher PA irrespective of ST level (interaction=0.64). We observed an inverse association between leisure time PA and the risk of CRC, particularly for rectal cancer. There was no association between ST and CRC in multivariable models.

Physical activities and influencing factors among public health nurses: a cross-sectional study

OBJECTIVES

Public health nurses are responsible for promoting and managing the health of community members, and if they do not have enough physical activity or ignore their own health, not only will their own health decline but the quality of life of the public will also be affected. This study investigated the physical activity of public health nurses and analysed the effects of attitudes, subjective norms, perceived behavioural control and behavioural intention to engage in physical activity.

METHODS

This study adopted a cross-sectional research design, and convenience sampling was used to select the research subjects. 198 public health nurses were invited to participate, and 172 completed the questionnaire. Multiple linear regression was used to analyse the influencing factors of physical activity intention and physical activity.

RESULTS

Attitudes towards physical activity and perceived behavioural control of physical activity affected physical activity intention. When they had higher behavioural intention, their physical activity behaviour also improved. The physical activity intention significantly influenced the number of days that they had engaged in vigorous physical activity (95% CI 0.1786 to 0.3060, p<0.0001), and significantly influenced the number of days that they walked daily for 10 min (95% CI 0.2158 to 0.4144, p<0.0001), and also significantly influenced their daily sedentary time (95% CI -0.3020 to 0.0560, p=0.0046).

CONCLUSIONS

Encouraging public health nurses to heed their own health and motivating them to engage in physical activity warrants attention from policy-makers and government health agencies.

Predicting Physical Activity and Healthy Nutrition Behaviors Using Social Cognitive Theory: Cross-Sectional Survey among Undergraduate Students in Chongqing, China

(1) Background: Generally suggested public health measures to reduce obesity were to limit television (TV) viewing, enhance daily physical activities, enable the consumption of fruit and vegetables, and reduce sugar-sweetened beverage intake. This study analyzed the extent to which selected social cognitive theory constructs can predict these behaviors among Chinese undergraduate students. (2) Methods: This cross-sectional study included 1976 undergraduate students from six universities in Chongqing, China. A self-administered five-point Likert common physical activity and nutrition behavior scale based on social cognitive theory was utilized. (3) Results: This study included 687 (34.77%) males and 1289 (65.23%) females. A total of 60.14% of the students engaged in exercise for less than 30 min per day. Approximately 16.5% of the participants spent at least 4 h watching TV and sitting in front of a computer daily. Approximately 79% of the participants consumed less than five cups of fruit and vegetables daily. Undergraduate students who had high self-efficacy scores had more leisure time physical activities. Those who have high expectation scores had considerable time watching TV and sitting in front of a computer. Undergraduate students who had high expectation and self-efficacy scores had substantially low consumption of sugar-sweetened beverages. Those who had high self-efficacy scores consumed considerable amounts of fruit and vegetables. Furthermore, the type of university, BMI group, gender, age, lack of siblings, and grade level were associated with the aforementioned four behaviors. (4) Conclusion: Physical inactivity and unhealthy nutrition behaviors are common among undergraduate students. This study used social cognitive theory to provide several implications for limiting the TV viewing, enhancing daily physical activities, consuming fruit and vegetables, and reducing sugar-sweetened beverage intake among undergraduate students.

Daily sedentary time and its association with risk for colorectal cancer in adults: A dose-response meta-analysis of prospective cohort studies

Sedentary behavior is emerging as an independent risk factor for health. However, previous studies have indicated that sedentary behaviors are associated with the colorectal cancer risk, but presented controversial results.Studies in PubMed and EMBASE were searched update to February 2017 to identify and quantify the potential dose-response association between daily sedentary time and colorectal cancer.Twenty-eight eligible studies involving a total of 47,84,339 participants with 46,071 incident cases were included in this meta-analysis. Our results showed statistically significant association between prolong television viewing time and colorectal cancer (odds ratio [OR] 1.17, 95% confidence interval [CI] 1.09-1.24, P < .001). Additionally, we obtained the best fit at an inflection point of 2 hours per day in piecewise regression analysis, the summary relative risk (RR) of colorectal cancer for an increase of 2 hours per day television viewing was 1.07 (95% CI 1.05-1.10, P < .001). Furthermore, prolong occupational sitting time was correlated with a significantly higher risk of colorectal cancer (OR 1.15, 95% CI 1.08-1.22, P < .001), increasing 2 hours per day of occupational sitting time per day was associated with a 4% incremental in the risk of colorectal cancer (RR 1.04, 95% CI 1.01-1.08). Additionally, prolong total sitting time was associated with a significantly higher risk of colorectal cancer (OR 1.06, 95% CI 1.03-1.09, P < .001). Increasing 2 hours of total sitting time per day was associated with a 2% incremental in the risk of colorectal cancer (RR 1.02, 95% CI 1.01-1.06). Subgroup meta-analyses in study design, study quality, number of participants, and number of cases showed consistent with the primary findings.Prolonged television viewing, occupational sitting time, and total sitting time are associated with increased risks of colorectal cancer.

Sedentary lifestyle related exosomal release of Hotair from gluteal-femoral fat promotes intestinal cell proliferation

Pioneering epidemiological work has established strong association of sedentary lifestyle and obesity with the risk of colorectal cancer, while the detailed underlying mechanism remains unknown. Here we show that Hotair (HOX transcript antisense RNA) is a pro-adipogenic long non-coding RNA highly expressed in gluteal-femoral fat over other fat depots. Hotair knockout in adipose tissue results in gluteal-femoral fat defect. Squeeze of the gluteal-femoral fat induces intestinal proliferation in wildtype mice, while not in Hotair knockout mice. Mechanistically, squeeze of the gluteal-femoral fat induces exosomal Hotair secretion mainly by transcriptional upregulation of Hotair via NFκB. And increased exosomal Hotair in turn circulates in the blood and is partially endocytosed by the intestine, finally promoting the stemness and proliferation of intestinal stem/progenitor cells via Wnt activation. Clinically, obese subjects with sedentary lifestyle have much higher exosomal HOTAIR expression in the serum. These findings establish that sedentary lifestyle promotes exosomal Hotair release from the gluteal-femoral fat, which in turn facilitates intestinal stem and/or progenitor proliferation, raising a possible link between sedentary lifestyle with colorectal tumorigenesis.

Controversies in the risk of neoplasia in GH deficiency

Growth hormone (GH) replacement in GH deficient (GHD) children secures normal linear growth, while in GHD adults it improves metabolic status, body composition and quality of life. Safety of GH treatment is an important issue in particular concerning the controversy of potential cancer risk. Unlike in congenital IGF-1 deficiency, there is no complete protection against cancer in GHD patients. Important modifiable risk factors in GHD patients are obesity, insulin resistance, sedentary behavior, circadian rhythm disruption, chronic low grade inflammation and concomitant sex hormone replacement. Age, family history, hereditary cancer predisposition syndromes or cranial irradiation may present non-modifiable risk factors. Quantifying the risk of cancer in relation to GH therapy in adult GHD patients is complex. There is evidence that links GH to cancer occurrence or promotion, but the evidence is progressively weaker when moving from in vitro studies to in vivo animal studies to epidemiological studies and finally to studies on GH treated patients. GH-IGF inhibition in experimental animals leads to decreased cancer incidence and progression. Epidemiological studies suggest an association of high normal circulating IGF-1 or GH to cancer incidence in general population. Data regarding cancer incidence in acromegaly are inconsistent but thyroid and colorectal neoplasias are the main source of concern. Replacement therapy with rhGH for GHD is generally safe. Overall the rate of de novo cancers was not increased in studies of GH-treated GHD patients. Additional caution is mandated in patients with history of cancer, strong family history of cancer and with advancing age. Childhood cancer survivors may be at increased risk for secondary neoplasms compared with general population. In this subgroup GH therapy should be used cautiously and with respect to other risk factors (cranial irradiation etc). We believe that the benefits of GH therapy against the morbidity of untreated GH deficiency outweigh the theoretical cancer risk. Proper monitoring of GH treatment with diligent cancer surveillance remains essential.